What is reversible expansion?
Hence, a reversible isothermal expansion is an infinitely-slow increase in volume at constant temperature. All the reversible isothermal PV work wrev done by an ideal gas to expand was possible by reversibly absorbing heat qrev into the ideal gas.
Is the process of expansion of the universe?
Based on large quantities of experimental observation and theoretical work, the scientific consensus is that space itself is expanding, and that it expanded very rapidly within the first fraction of a second after the Big Bang. This kind of expansion is known as “metric expansion”.
Why free expansion is irreversible?
Heat has been transferred to the surroundings increasing its entropy. Thus there is a positive total entropy change of the universe (system + surroundings) making the entire process irreversible.
Do reversible processes exist?
Since it would take an infinite amount of time for a reversible process to finish, perfectly reversible processes are impossible. However, if a system undergoing the change by a process responds much faster than the applied change by the process, then the deviation from reversibility may be negligible.
Which process is reversible?
A thermodynamic process is reversible if the process can return back in such a that both the system and the surroundings return to their original states, with no other change anywhere else in the universe. It means both system and surroundings are returned to their initial states at the end of the reverse process.
Why is the universe believed to be expanding?
Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart. One explanation for dark energy is that it is a property of space. As a result, this form of energy would cause the universe to expand faster and faster.
How can the universe be infinite and expanding?
Although space may have been concentrated into a single point at the Big Bang, it is equally possible that space was infinite at the Big Bang. In both scenarios the space was completely filled with matter which began to expand. There is no centre of the expansion, the universe is simply expanding at all points.
Is free expansion always irreversible?
The free expansion of a gas is an irreversible process; in principle, the temperature of a gas undergoing a free expansion is not a meaningful quantity.
Why is Joule expansion irreversible?
For example, Joule expansion is irreversible because initially the system is not uniform. Thus, if the system is always uniform, then the process is reversible, meaning that you can return the system to its original state by either adding or removing heat, doing work on the system, or letting the system do work.
Are there irreversible processes in nature?
An irreversible process is what we encounter in reality almost all the time. The system and its environment cannot be restored to their original states at the same time. Because this is what happens in nature, it is also called a natural process. This phenomenon is called irreversibility.
What is irreversible and reversible process?
A reversible process is one in which both the system and its environment can return to exactly the states they were in by following the reverse path. An irreversible process is one in which the system and its environment cannot return together to exactly the states that they were in.
Which proves that the universe is expanding?
The observations that most of the universe exhibits a red shift in the spectrum. Objects moving away from an observed exhibit a red shift. This is because as the object moves away the waves are spread further apart. The red shift as explained by the doppler effect shows that the universe is expanding.